The invention concerns a flat air filter element, in particular for an air filter in the air intake manifold of an internal combustion engine, as well as an air filter.
Air filters are employed in the air intake manifold in internal combustion engines, for example, in motor vehicles, in order to remove contaminants from the combustion air to be supplied to the internal combustion engine. When the combustion air passes through a filter medium of the air filter, a pressure loss occurs which may reduce the power of the internal combustion engine. In order to reduce the pressure loss, a filter surface of the filter element can be enlarged. However, an installation space which is available for the air filter is often greatly limited, for example, in the engine compartment of a motor vehicle, so that the air filter cannot be enlarged sufficiently.
DE 10 2010 053 200 A1 discloses a filter element for an interior filter of an air conditioning or ventilation system that comprises a pentagonal bellows wherein the bellows is comprised of a first rectangular partial bellows and a second quadrangular partial bellows. In this way, the quantity of waste of filter material when manufacturing the pentagonal bellows can be reduced.
DE 203 10 833 U1 discloses a filter insert for installation in a flow channel with a predetermined installation cross section. The filter insert comprises an outer contour which is adapted to the installation cross section of the flow channel, wherein a plastic part is placed onto a bellows in order to adapt the folded bellows to the installation cross section. The bellows can be cut to a trapezoidal shape in order to avoid waste.
EP 1 144 083 B1 shows an air filter for internal combustion engines that comprises a housing with a cover in which a filter insert is inserted. The housing comprises a stay which extends through a cutout in the filter insert between two wall parts of the housing to be reinforced. In this construction, complex sealing measures in the region of the cutouts of the filter insert are required so that the manufacture of the filter insert is made difficult and more expensive. Moreover, there is the risk of damaging the filter insert during installation of the filter insert.
The web page accessible at www.dnafilters.com/en/technology/the-anatomy-of-a-dna-high-performance-filter.html (retrieved on Mar. 21, 2016) describes an air filter insert for motorcycles which comprises a filter medium of oil-impregnated cotton. The filter medium is arranged between two metal mesh layers and within a rim structure of polyurethane wherein a circumferentially extending seal of ethylene vinyl acetate is inserted in the rim structure. The rim structure and the filter medium may have a complex outer circumferential geometry with recesses. A reliable sealing seat in a filter housing cannot be ensured easily with the known air filter element. Also, due to the material composition of the air filter element, a future disposal or recycling of the air filter is made difficult.